Lawn mower sharpener



June l5, l1943. .1. R. TEDD LAWN MOWER SHARPENER' 2 sheets-sheet 1 Filed Dec. 27. 1940 /NL-N TD5' L url/"IE5 Fe. TEDD. 4

m- TDH/v5 June 15, 1943.l 1. R. TEDD 2,321,953

LAWN MOWER SHARPENER Filed Dec. 2'7,` 1940 2 sheets-sheet 2 NL/vTU/ dn M55 R'. TEUU mw FI T TURA/EY Patented .lune 15, i943 Unirse sTATEs amsn LAWN Morvan snanrnnne .lames R. Tedd, Willamette, Greg. Applicata@ December 27, 1940, serial No. 371,973

' (c1. vs -82.1)

1 Claim.

This invention relates generally to tool sharpening devices and particularly to a lawn .mower ing operation may be satisfactorily performed by an unskilled person.

The third object is to construct a sharpener'of e the class described in a manner that regardless oi how distorted or uneven the blades of a mower may be, they may be easily placed in a proper'y cutting condition with the utmost precision after which the lawn mower may be resharpened at any time with very little eiort. y

The fourth object is to so construct a lawn mower Sharpener that the proper angles of clearance along the stationary and moving cutting:v

edges may be established and maintained at all times.

The fifth object is to so construct a Sharpenerk that the cutting operation is entirely in the nature of a shear instead of tearing or wearing thev blades of grass by rubbing them between engaging surfaces as is commonly the case.

I accomplish these and other objects in thel manner set forth in the following specification as illustrated in the accompanying drawings, in which:

Fig 1 is a plan of a lawn mower showing the sharpener mounted thereon.

Fig. 2 is an elevation of Fig. 1.

Fig. 3 is an end elevation of Fig. 1.

Fig. 4 is a transverse section taken along the line 4--4 in Fig. 2.

Fig. 5 is an elevation of the sharpener itself taken along the line 5--5 in Fig. 4 showing one of the cutter blades developed along a straight line.

Fig. 6 is a transverse section similar to Fig. 4 but showing a modified form of mower construction in which the brace rod is along the aXis of the mower wheels.

Fig. 7 is a fragmentary section taken along the line 'I-'I in Fig. 4.

Fig. 8 is a section taken along the line 8 8 in Fig. 5.

Fig. 9 is a transverse section through the stationary cutter bar showing the manner of truing Same.

Fig. 10 is a transverse section taken along the line IIB--I in Fig. 1. 1

Fig. 11 is a fragmentary section 'taken 'along the line II-II in Fig. 1.

Similar numerals refer to similar parts throughout the several views.

Referring in 'detail to the drawings, there `i shown a mower, including the drive wheels IBA which are mountedY on the sideframes I IA, which frames are held in spaced relation at one end by means of a brace rod I2 and at' the other end by means of the stationary cutter bar I3. The usual roller I4 is rotatably mounted between the ends I5 of the said frames I I. Journaling in the side frames II is the shaft I6 which is driven from the wheels ISA in the manner common to most lawn mowers, namely: an internal gear and pinion drive.' The position of the cutter bar clamping bolts I1 is also indicated.

Referring more' particularly to my invention, the same will be seen to consist of three distinct parts,.namely: a guide rod I8 whchmust be held parallel with the brace rod I2 supporting standards I9 for the guide rodr I8 kandthe transverse slideable Vigile.' holding bar 2D bymeans of which thesharpenirlg Operation is performed.

'Referring in detail to, the'gude rod I8 shown injFig.-l0,the' same willbe seento consist of a round rod lhaving a attened'face 2l formed thereon, to enable same' to be used as a straight edge for checking thealignment of the stationary cutter bar I3.

" The guide rod I8v is slidably mounted at each end"V in the bracket 22 through which is threaded the 'vertical'screw 23, whose lower end 24 is reduced in diameter and journals vin the lug 25 which projects from the standard I9. The upper end 26 of the screw 23 has the threads removed therefrom to freely receive the nut 21 which rests upon the uppermost thread and prevents the screw 23 from rising out of its support inthe lug 25. The end 26 journals in the enlarged hole 28 in the laterally turned upper end 26 of the standard I9.

The le holding bar 20 is a straight bar of flat stock and has secured on one end thereof a backwardly turned bar 29 whose angularity in relation to the le holding bar 20 is determined by the set screw 353. On the under side of the bar 29 is attached a saddle 3| adapted to ride accurately upon the guide rod I8. The position of the saddle 3| with relation to the member 29 may be fixed.

ride accurately upon the brace rod I2, the saddle 32 may be held in a desired position by means of the set screw 33.

Between the saddles 3| and 32 and adjustably mounted on the bar 20 is the le holder 34 which is adapted to receive a short section of file 35 and to be clamped to the bar 20 by means of the set screws St.

In order to true up the stationary cutter bar I3, it is necessary to have a straight flat file 31 which can be laid on a flat support 38, as shown in Fig. 9.

In the form of the device shown in Fig. 6, the brace rod 39 is disposed along the axis of the wheels IGA which practice is sometimes followed and the illustration is made merely to indicate the adaptability of my sharpener to different types of lawn mowers.

In order to make the standards I9 adaptable to any mower of this type, I have formed a `fla-ring slot 43 at the lower end thereof in order t0 freely receive the clamping bo-lts I1 and to pivotally support each of the standards I9 .until their correct position is established.

It is understood that .the stationary cutter bar Y I3 is removably mounted on the cutter bar Vframe 4I which is tiltable Q11 the bolts II.

The operation of the sharpener is as follows: The c utter bar I3 is rst removed from its frame 4I and drawn aCIOsS the flat le 31 in a manner shown Vin Fig. 9 in order to true the face 43, the angularity of the egg-e 44, may be similarly ccrrected and checked by .CDmDaring it with the straight face 2j .of the guiderod I8. Bar I3 is then put into its correct rposition in the mower and the standards I ElV are put into the position shown in Fig. 3. The guide rod I8 is then put in position and the bar 20 is placed transversely across the rods I2` and I8 .by .engaging the saddles 3| and 32, the latter being moved longitudinally along the bar 20y until the desired position is found and then clamped by meansof the screw 33. The le holder 34 Iis now moved longitudinally along the bar 20 until the le 3,5 engages the cutting face .45 of the ,spirally shaped cutting blade 46 which is mounted on the spokes 41 which radiate around the shaft I6. Starting from the assumption that the rods I2 and I8, as well as the face 43, vare straight, itbecomes necessary to bring the axes of the rods. I2 Vand I8 in parallelism, with each other, vas well as in the same plane. The former is accomplished by adjusting the angularity of the standards I9 to meet the spacing action of the saddles 3| and 32, while the rods I2 and I8 are brought into the same plane by turning the screws 23 in the required direction, then by checking a, given blade 46 with relation to the stationary bar I3, the precision adjustment is completed by turning the screw 30.

The ends 48 of the bar 20 are now grasped by the two hands of the operator and the bar 20 is moved longitudinally along the length of the mower, care being taken to hold the bar 20 as nearly as possible normal to the axis of the wheels I EJA. As the file 35 is moved longitudinally, it follows that the blade 46, which is spirally formed, mustrotate to conform to the position of the file in relation to which it is held by means of the edges 49 of the file holder 34.

As the high spots on the cutting face 45 of a blade 46 are led down, further adjustment is made by means of the screw 3B until the correct relationship between a given blade 46 and the stationary bar I3 is obtained. The same process is repeated for each of the blades 46. It is desirable to number Aor otherwise identify the various'blades 46 to ,facilitate the sharpening process. It can be see-n from the foregoing' thatthe .same practice may be followed in any mower having a lateral ybrace rod I2 or a vcentral brace. rod 39, it merely requiring a .different positioning of the saddle ,32.

I am aware that many `for-ms of `lawn mower Sharpeners have .been constructed in .the past. It is, therefore, Inot my intentions to cover such devices broadly but I do intend tocover al1-such forms and modifications thereof .as fall fairly within the appended claim.

I claim:

In a precision grinder fo-r lawn mowers of. the 'types having a brace bar, a stationary cutter bar, and a plurality of curved blades rotating to engage the cutter bar; a rigid guide bar, means fer securing said guide bar in exact parallelism with the axis of rotation of the curved lawn mower blades and the .axis .of the brace bar in a position so that the point of sharpening is substantially inthe plane passing through theaxis of theguide bar `and the axis of the brace bar, and a fileholding assembly slidable on the brace bar of the mower and .on said rigid guide bar, said assembly including guide4 means engaging the two parallel bars for holdingv theassemblynormal toits line of sliding movement as the le engages the cutting edges of the curved blades, whereby the bearing faces` of4 the guide means may also lie close to said plane, thus avoiding long stems for the guide means.

JAMES R. TEDD. 

